Piston sealing arrangements, e.g. in brake force regulators, are known. For example, ring seals of different profile are rigidly fitted in an annular recess of the piston or its housing. Depending on the piston's cross-section and on the force which presses the piston against its stop, for instance by a preloaded spring, a specific initial pressure is required to move the piston in opposition to this force. In the presence of great initial pressure, the ring seal deforms elastically before the piston starts to move. The axial thickness of the ring seal, that is viewed in relation to the piston axis, decreases while the radial thickness thereof increases. Due to this, the ring seal is pressed tightly against the walls to be sealed relative to one another, and upon attainment of the initial pressure the piston first has to overcome a high amount of static friction before it yields the pressure. This has as a result a jerky initial movement of the piston afflicted with a hysteresis (stick-slip effect).
Attempts have been made to avoid this by reducing the friction values and by optimizing the sealing edge. However, these attempts met with only little success. Moreover, a precisely machined sealing edge is susceptible wear.